(1) Field of the Invention
The present invention relates to a novel olefin copolymer composition. More particularly, the present invention relates to an olefin copolymer composition which is suitable as a material for single-layer films, laminated films, and the like, can provide molded items excellent, for example, in heat-sealing properties, transparency, blocking resistance, and surface gloss, and is good in processability.
(2) Description of the Related Art
Polypropylene resins have heretofore been widely used, for example, in the field of films by virtue of their excellent mechanical properties such as stiffness and impact strength as well as their excellent optical properties. However, these polypropylene resins have a defect that the film formed therefrom alone has a high heat-sealing temperature.
In view of this, there was proposed a composition prepared by blending a polypropylene resin with a butene-1 copolymer in order to improve the heat-sealing properties of polypropylene film (Japanese Patent Laid-Open Nos. 108646/1986, and 108647/1986). However, this composition has a defect that the transparency of the film prepared therefrom lowers because the butene-1 copolymer used for the composition which is prepared by solution polymerization using a catalyst carried on magnesium chloride has a narrow molecular weight distribution, and is not enough high in processability.
The butene-1 copolymer obtained using titanium trichloride as a catalyst is low in randomness and poor in transparency, and therefore the polypropylene type film obtained from the composition prepared by blending it is inevitably not high enough in transparency.